If you mean the track models, yes ramps may be a little tough because it's not gonna fit perfectly and you have to approximate rotation of the track model.
a) you can actually use math to get a somewhat perfect angle, specifically atan(rise:run) is the formula for general angle that you can afterwards tweak.
b) nobody gives a damn about misaligned rails. Seriously, if they look like rails from 10 meters, that's enough. Try looking closer at them in official maps and you'll find that they're never perfect.